1. Field of the Invention
The present invention relates to a magnetic recording apparatus for use as a video tape recorder, and more particularly to a magnetic recording apparatus having a means for determining a recording current.
2. Description of the Prior Art
Magnetic recording apparatus such as video tape recorders, for example, record and reproduce audio and video signals (hereinafter also referred to as audio/video signals) and are adjusted to a predetermined record/reproduce level in the factory. Recording currents representative of audio/video signals are supplied to magnetic heads by which they are recorded on a magnetic tape, or reproduced currents representative of recorded audio/video signals are supplied from magnetic heads by which they are reproduced from the magnetic tape. Since the audio/video signals, i.e., the recording currents or the reproduced currents are fixed in level, they cannot be adjusted by the user of the magnetic recording apparatus.
When the magnetic heads are worn and their performance varies after a long period of use, since the recording currents are of fixed level, they deviate from optimum recording current values. As a result, the signal-to-noise ratio of a reproduced image tends to be deteriorated, and a reproduced sound tends to be distorted because of the wear of the magnetic heads.
One solution would be to initially set recording currents to values that deviate from the values of optimum recording current in order to make up for eventual wear of magnetic heads. When the magnetic heads have been used and worn after a long period of use, the recording currents would be equalized to the optimum recording currents. However, the recording currents would not be equal to the optimum recording currents when the magnetic heads are initially used, and the recording currents would not remain equal to the optimum recording currents after the optimum recording currents had been reached. Therefore, the initial recording current adjustment would not completely solve the aforesaid problem.
Various different types of magnetic tapes, including an oxide tape, a high-energy oxide tape, a metal-powder tape, a metal-evaporated tape, etc., have different recording characteristics. However, since desired audio/video signals are recorded with a constant-level recording current in the conventional magnetic recording apparatus, the magnetic recording characteristics of the different magnetic tape types are not fully utilized.